1. Technical Field
The following description relates to one or more image readers configured to read an image of a document sheet, particularly to one or more image readers that has a first image reading unit configured to read an image on a first side of a document sheet being conveyed along a feeding path and output an analog signal corresponding to the read image of the first side, and a second image reading unit configured to read an image on a second side of the document sheet being conveyed along the feeding path and output an analog signal corresponding to the read image of the second side.
2. Related Art
So far, an image reader configured to read an image of a document sheet has been applied to various devices such as an image scanner, a copy machine, and a facsimile machine. To attain a function of the image reader of this kind to read images on both sides of a document sheet, an image reader has been proposed that has a single image reading unit configured to read the images on the both sides of the document sheet by reversing the document sheet on an improved feeding path. In addition, recently, an image reader has been proposed that is configured to read images on both sides of a document sheet together using two image reading units.
For example, in an image reader which has a first image reading unit configured to read an image on a first side of a document sheet being conveyed along a feeding path and output an analog signal corresponding to the read image of the first side, and a second image reading unit configured to read an image on a second side of the document sheet being conveyed along the feeding path and output an analog signal corresponding to the read image of the second side, it is possible to perform, in parallel, an operation of reading the image on the first side using the first image reading unit and an operation of reading the image on the second side using the second image reading unit. Thus, it is possible to enhance a reading speed for reading the both sides of the document sheet. Further, in the image reader of this kind, the first image reading unit and the second image reading unit are connected with respective separate analog front ends (AFEs) such that the analog signal output from each image reading unit is individually converted into a digital signal.